Liu H.-Y.,Beijing University of Technology |
Liu H.-Y.,Tibet University |
Liu H.-Y.,Key Laboratory on Deep GeoDrilling Technology |
LU S.-R.,Capital University of Economics and Business |
And 2 more authors.
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2014
According to the dynamic deformation characteristics of the persistent jointed rock mass and the relevant results of the existing rock dynamic constitutive models, the dynamic stress of the persistent jointed rock mass is regarded as the summation of two components, which are the static stress and the dynamic stress components respectively. The static stress component of the persistent jointed rock mass is simulated using three basic deformation components connecting in series such as the nonlinear component reflecting the rock mesoscopic damage, joint closure and shear deformation components. The dynamic stress component is simulated using the viscous component. Then the uniaxial dynamic compression damage constitutive model is set up. Next, according to the fact that the persistent jointed rock mass often shears to fail along the joint face under the uniaxial load, the joint shear failure criterion is introduced into the damage constitutive model established above to revise it, which can perfectly consider the effect of the joint shear strength on this model, and the uniaxial compression damage constitutive model of persistent jointed rock mass considering the joint shear strength is established finally. Then this model is adopted to calculate the mechanical properties of the persistent jointed rock mass under compression load, and the effect law of the joint dip angle on the rock mass uniaxial compression dynamic climax strength is especially discussed. The results show that the failure modes of the jointed rock mass include the tensile or shear failure of the intact rock, the shear failure along the joint face and the mixed one of the above two ones with the joint dip angle, and accordingly the uniaxial compression dynamic climax strength of the jointed rock mass greatly varies with it. Source
Hao Y.,China University of Geosciences |
Hao Y.,Key Laboratory on Deep GeoDrilling Technology
Chemistry and Technology of Fuels and Oils | Year: 2015
The influence of stratum properties on wellbore stability was studied by numerical simulation. The results showed that the safe mud density window (SMDW) for both permeable and impermeable strata becomes narrower with increase in the ground stress non-uniformity coefficient. The probability of wellbore wall instability increases where the strata are permeable. If the ground stress non-uniformity coefficient is constant in this case, then there is a linear increase in the pressure at which stability loss and wellbore-wall collapse occur and a linear increase in stratum fracture pressure (SFP). Here, fracture pressure increases more rapidly than collapse pressure. The SMDW narrows with rise in pore pressure and widens with an increase in stratum tensile strength and the cohesive force between molecules. The SMDW is wider for permeable strata than for impermeable strata in this case. The width of the SMDW also increases with an increase in the internal friction angle, but it becomes narrower with an increase in the effective stress. The SMDW is not affected by increases in the Poisson's ratio or porosity if there is no permeation but becomes smaller if there is permeation. In the absence of a supporting force, wellbore stability decreases drastically and the formation near the wellbore also becomes unstable. © 2015 Springer Science+Business Media New York. Source
Zhao Y.,University of Science and Technology Beijing |
Liu H.,Beijing University of Technology |
Liu H.,Tibet University |
Liu H.,Key Laboratory on Deep GeoDrilling Technology |
And 3 more authors.
Zhongnan Daxue Xuebao (Ziran Kexue Ban)/Journal of Central South University (Science and Technology) | Year: 2015
The jointed rock mass damage constitutive model based on coupling of macroscopic and mesoscopic flaws was proposed. Firstly, the rock damage model which only considers the effect of mesoscopic flaws such as microcracks and the jointed rock mass damage model which only considers the effect of macroscopic flaws such as joints were introduced respectively. Secondly, the compound damage variable based on coupling the macroscopic and mesoscopic flaws was deduced based on the Lemaitre strain equivalence hypothesis, and then the damage constitutive model of jointed rock mass based on coupling macroscopic and mesoscopic flaws was set up. Finally, the rock uniaxial compression test data was adopted to validate this model. The results show that this model can perfectly reflect the effect of the two kinds of flaws on the rock mass stress-strain curve at the same time. Meanwhile, the stress-strain curves of the jointed rock mass with a single different dip angle joint and many parallel joints under uniaxial compression load are analyzed. The obtained results fit very well with the experimental and theoretical results in relevant references, which indicate the rationality of this model. ©, 2015, Central South University of Technology. All right reserved. Source
He L.Z.,Beijing University of Technology |
He L.Z.,Key Laboratory on Deep GeoDrilling Technology |
Zhou Q.,Beijing University of Technology |
Zhou Q.,Key Laboratory on Deep GeoDrilling Technology |
And 3 more authors.
Advanced Materials Research | Year: 2014
The double-circular-arc gear bearing capacity is the key problems for realizing the low speed and high torque work demands of small-diameter deep-well turbodrill reducer. Double double-arc gear shaft structure is adopted for improving the gear bearing capacity Based on the 2K-H-NGW type planetary gear transmission. Increase modulus and decrease teeth number properly can improve the double-circular-arc gear capacity on the premise of limited radial size. This article analyze the gear bending stress based on ANSYS and simulation results show that stress mainly concentrated on tooth root and tooth waist area and maximum loading is at tooth waist area. The simulation maximum bending stress is 289N/mm2 and the theoretical bending stress is 277.50N/mm2.The two results are basically identical. It is consistent with the actual work situation. © (2014) Trans Tech Publications, Switzerland. Source
Wang G.,Beijing University of Technology |
Wang G.,Key Laboratory on Deep GeoDrilling Technology |
Zhang Q.,Beijing University of Technology |
Huang X.,Beijing University of Technology |
And 3 more authors.
Przeglad Elektrotechniczny | Year: 2013
Pile anchor supporting structure is a common method in deep foundation pit engineering. To a certain extent, anchor forces can reflect the earth pressure acting on the supporting structures. In the process of the deep foundation pit construction, the layers with different types of groundwater are often encountered. Improper control of groundwater may lead to engineering safety problems and many other cases which can cause bad effects on the surrounding environment. Therefore, it is of practical significance to conduct the optimal designs for supporting structures of deep foundation pit by monitoring the anchor forces in-situ. Through studying and analyzing the monitoring data, the earth pressure's magnitude and distribution law can be further understood. In this paper, foundation pit engineering is taken as a base, a whole monitoring of the actual anchor forces is made in the process of tensioning, locking and working of anchors, and the monitoring data is analyzed. A numerical analysis based on the fluid-solid coupling theory of unsaturated soil is performed, and tests of the soil water characteristic curve (SWCC) for typical unsaturated soil are carried out. Finally, the test results are applied to numerical analysis. The results of anchor forces calculated by considering the coupled condition and ignoring the groundwater's effect are compared with the monitoring results of engineering site. The comparison indicates that numerical results are inconsistent with measured results. The numerical results are close to the measured results only when the fluid-solid coupling theory of unsaturated soil is considered. Source